In general, mobile terminals (for example, smartphones, PDAs, tablet computers and the like) are provided with a display device such as a liquid crystal display device or an organic EL display device. Recently, the display device is equipped with an additional function such as a touch sensor or the like.
Incidentally, for example, a display device which enables the touch sensor to operate in a blank period of liquid crystal drive is well known as a liquid crystal display device having a touch sensor function built in a display panel. Since panel drive load is varied in a display drive period (hereinafter called a display period) of the liquid crystal and a sensing operation period (hereinafter called a non-display period) of the touch sensor, load variation often occurs cyclically on the display panel when the display period and a touch period are cyclically set. At this time, a booster circuit and a regulator for the liquid crystal drive cannot follow the load variation and ripple (noise) occurs in a power supply voltage. The ripple has a risk of causing various disadvantages to the liquid crystal display device.